Novelties of a superacidic mesoporous catalyst UDCaT-5 in alkylation of phenol with tert-amyl alcohol

摘要

Alkylation of phenol is industrially important and several catalytic processes are developed. In the current work, the efficacies of several novel solid superacids designated as UDCaT-4, -5 and -6, and of sulphated zirconia were studied in liquid phase alkylation of phenol with tert-amyl alcohol. UDCaT-4, -5 and -6 are mesoporic superacids. The activity was found to be in order UDCaT-5 > UDCaT-6 > UDCaT-4 > sulphated zirconia. The high sulphur content present in UDCaT-5 was found to be responsible for the greater activity at 120 degrees C. The formation of products is correlated with the acidity of the catalyst. The conversion of tert-amyl alcohol and the selectivity for C-alkylated product were 96 and 85%, respectively, under optimum reaction conditions. The reaction was carried out without solvent in order to make the process cleaner and greener. The effects of various parameters on rates and product distribution are used to deduce the kinetics of the reaction. A second-order rate equation fits the data well under the assumption that both phenol and the alkylating agents are weakly adsorbed. The apparent activation energy was determined to be 8.57 kcal/mol. An independent dehydration study of tert-amyl alcohol was done. (c) 2005 Elsevier B.V. All rights reserved.